1. Field of the Invention
The present invention relates to an electrophotographic element, in particular relates to an electrophotographic element which comprises providing an intermediate layer having a specified function on an electrically conductive substrate and providing a photosensitive layer (photoconductive layer) on said intermediate layer. In the electrophotographic element according to the present invention, carriers are recombined on the interface between the photoconductive layer and the intermediate layer, whereby residual electric potential is reduced remarkably.
2. Description of the Prior Art
As the representative examples of photoconductive materials used in the electrophotographic element there have usually been enumerated inorganic materials such as Se, ZnO, CdS and the like and organic materials such as poly-N-vinylcarbazole (PVK), trinitrofluorenone (TNF) and the like. Recently, however, amorphous silicon (which is sometimes called "a-Si" hereinafter) has come to attract public attention. The reason is considered to consist in that the use of the electrophotographic element employing a-Si as the photoconductive layer (photosensitive layer) brings about constantly stable electrophotographic characteristics and therefore high quality images can always be obtained.
However, the fact is that conventional a-Si electrophotographic elements hold the following defects substantially in common: (1) Said elements are insufficient in chargeability due to severe dark decay, (2) Said elements cause blurred images and white-spot portions in images while being used actually in copying machines (or printing machines), (3) Said elements are susceptible to contaminants on the substrate surfaces and consequently abnormal images are caused, (4) Said elements are insufficient in high temperature resistance and high humidity resistance, and the like. This tendency can be observed also in conventional inorganic or organic electrophotographic elements, apart from great and small degrees, and therefore more improvement is demanded therefor.